The present invention pertains to novel microorganisms of the genus Lactobacillus, that are useful in preventing diarrhoea brought about by pathogenic bacteria. In particular, the present invention relates to the use of said microorganisms for the preparation of an ingestable support and to a composition containing the same.
Organisms that produce lactic acid as a major metabolic component have been known for a long time. These bacteria may be found in milk or in milk processing factories, respectively, living or decaying plants but also in the intestine of man and animals. These microorganisms, summarized under the term xe2x80x9clactic acid bacteriaxe2x80x9d, represent a rather inhomogeneous group and comprise e.g. the genera Lactococcus, Lactobacillus, Streptococcus, Bifidobacterium, Pediococcus etc.
Lactic acid bacteria have been utilized as fermenting agents for the preservation of food taking benefit of a low pH and the action of fermentation products generated during the fermentative activity thereof to inhibit the growth of spoilage bacteria. To this end, lactic acid bacteria have been used for preparing a variety of different foodstuff such as cheese, yogurt and other fermented diary products from milk.
Quite recently lactic acid bacteria have attracted a great deal of attention in that some strains have been found to exhibit valuable properties to man and animals upon ingestion. In particular, specific strains of the genus Lactobacillus or Bifidobacterium have been found to be able to colonize the intestinal mucosa and to assist in the maintenance of the well-being of man and animal.
In this respect, EP 0 768 375 discloses specific strains of the genus Bifidobacterium, that are capable to become implanted in the intestinal flora and may adhere to intestinal cells. These Bifidobacteria are reported to assist in immunomodulation, being capable to competitively exclude adhesion of pathogenic bacteria to intestinal cells, thus assisting in the maintenance of the individual""s health.
During the last few years research has also focused on the potential use of lactic acid bacteria as probiotic agents. Probiotics are considered to be viable microbial preparations which promote the individual""s health by preserving the natural microflora in the intestine. A microbial preparation may be commonly accepted as a probiotic in case the effectual microbes thereof and their mode of action are known. Probiotics are deemed to attach to the intestine""s mucosa, colonize the intestinal tract and likewise prevent attachment of harmful microorganisms thereon. A crucial prerequisite for their action resides in that they have to reach the gut""s mucosa in a proper and viable form and do not get destroyed in the upper part of the gastrointestinal tract, especially by the influence of the low pH prevailing in the stomach.
In this respect, WO 97/00078 discloses a specific strain, termed Lactobacillus GG (ATCC 53103), as such a probiotic. The microorganism is particularly employed in a method of preventing or treating food induced hypersensitivity reactions in that it is administered to a recipient together with a food material that has been subjected to a hydrolysis treatment with pepsin and/or trypsin. The Lactobacillus strain selected is described as exhibiting adhesive and colonizing properties and showing a protease enzyme system, so that the protein material contained in the foodstuff to be administered is further hydrolyzed by means of proteases secreted by the specific Lactobacillus strain. The method discussed in this document shall eventually result in the uptake of protein material by the gut that does not show a substantial amount of allergenic material anymore.
Further, in EP 0 577 903 reference is made to the use of such lactic acid bacteria having the ability of replacing Heliobacter pylori, the acknowledged cause for the development of ulcer, in the preparation of a support intended for the therapeutic or prophylactic treatment of an ulcer associated with the action of Heliobacter pylori. 
In knowledge of the valuable properties particular strains of lactic acid bacteria may provide, there is a desire in the art for additional lactic acid bacterial strains that are beneficial to the well being of man and/or animal.
Consequently, a problem of the present invention is to provide additional bacterial strains that exhibit new properties beneficial for man and/or animals.
The above problem has been solved by providing novel microorganisms, namely lactic acid bacteria, belonging to the genus Lactobacillus having the capability of preventing colonization of the intestine with pathogenic bacteria causing diarrhoea.
According to a preferred embodiment the Lactobacillus strain is capable of adhering to the intestinal mucosa of mammal and may grow in the presence of up to 0.4% bile salts.
Yet, according to another preferred embodiment the lactic acid bacterium is selected from the group consisting of Lactobacillus rhamnosus or Lactobacillus paracasei, preferably Lactobacillus paracasei, and is more preferably Lactobacillus paracasei CNCM I-2116.
The microorganisms of the present invention have been shown to exhibit inter alia the following properties: they are gram positive, catalase negative, NH3 form arginine negative and CO2 production negative, they produce L(+) lactic acid, are capable to grow in the presence of bile salts in a concentration of up to about 0.4% and may essentially prevent colonization of intestinal cells by bacteria bringing about diarrhoea, such as pathogenic E. coli, e.g. enteropathogenic E.coli (EPEC), or salmonella, e.g. salmonella typhimurium. 
The novel microorganisms may be used for the preparation of a variety of ingestable support materials, such as e.g. milk, yogurt, curd, fermented milks, milk based fermented products, fermented cereal based products, milk based powders, infant formulae and may be included in the support in an amount of from about 105 cfu/g to about 1011 cfu/g. For the purpose of the present invention the abbreviation cfu shall designate a xe2x80x9ccolony forming unitxe2x80x9d that is defined as number of bacterial cells as revealed by microbiological counts on agar plates.
The present invention also provides a food or a pharmaceutical composition containing at least one of the Lactobacillus strains having the above traits and/or containing a supernatant of a culture, in which the microorganisms have been grown or a fraction thereof, respectively.
For preparing a food composition according to the present invention at least one of the Lactobacillus strains of the present invention is incorporated in a suitable support, in an amount of from about 105 cfu/g to about 1011 cfu/g, preferably from about 106 cfu/g to about 1010 cfu/g, more preferably from about 107 cfu/g to about 109 cfu/g.
In case of a pharmaceutical preparation the product may be prepared in forms of tablets, liquid bacterial suspensions, dried oral supplements, wet oral supplements, dry tube feeding or a wet tube feeding with the amount of Lactobacillus strains to be incorporated therein being in the range of up to about 1012 cfu/g, preferably from about 107 cfu/g to about 1011 cfu/g, more preferably from about 107 cfu/g to about 1010 cfu/g.
The activity of the novel microorganisms in the individual""s intestine is naturally dose dependent. That is, the more the novel microorganisms are incorporated by means of ingesting the above food material or the pharmaceutical composition the higher the protective and/or curing activity of the microorganisms. Since the novel microorganisms are not detrimental to mankind and animals and have eventually been isolated from baby feces a high amount thereof may be incorporated so that essentially a high proportion of the individual""s intestine will be colonized by the novel microorganisms.
Yet, according to another preferred embodiment the supernatant of a culture of a Lactobacillus strain of the present invention may be used for preparing one of the above ingestable support. The supernatant may be used as such or may well be dried under conditions that do not destroy the metabolic compounds secreted by the microrganisms into the liquid medium, such as e.g. freeze drying, and may be included in the carrier. In order to minimize the number of unknown compounds in the supernatant the Lactobacilli strains will preferably be grown in a defined media, the composition of which is known and does not negatively affect the host incorporating it. Further, the skilled person will, based on his general knowledge optionally deplete the supernatant from unwanted products, such as e.g. by means of chromatography.